"Fight Ippatsu! Jūden-chan!! Hitō Jūdan Tenkū Onsen" is a comedic and ecchi anime series that blends supernatural elements with slice-of-life scenarios. The story centers on Plug, a cheerful and somewhat naive "Jūden-chan" (a Charging Maiden) from the alternate dimension of Joule, where energy is the primary resource. Her mission is to travel to Earth and recharge the "energy-deprived" inhabitants by delivering electric shocks through a special plug-shaped device. However, her methods often lead to chaotic and humorous situations.

The protagonist, Ikkitōsai Sakura, is a kind-hearted but unlucky young man who frequently finds himself on the receiving end of Plug's charging antics. Despite the initial misunderstandings and mishaps, Ikkitōsai forms a bond with Plug and becomes her guide on Earth. The series explores their daily lives as they navigate the challenges of Plug's mission, her lack of understanding of human customs, and the comedic misunderstandings that arise from her actions.

Other characters include Honoka, a stoic and serious Jūden-chan who serves as Plug's rival, and Biffesta, a mischievous and unpredictable being who often complicates matters for the main cast. The narrative occasionally shifts to the floating hot spring resort, Tenkū Onsen, where characters from both dimensions interact, adding further layers of humor and absurdity to the story.

The plot is episodic, with each episode focusing on Plug's attempts to recharge individuals while learning about human emotions and relationships. The series balances its comedic tone with moments of lighthearted drama, often highlighting the growing friendship between Plug and Ikkitōsai. The interplay between the characters, combined with the absurd premise, creates a whimsical and entertaining narrative that emphasizes humor and camaraderie.